Electromagnetic wave absorbing sheets for preventing the leak and intrusion of electromagnetic waves are used in communications equipments such as cell phones, smartphones, wireless LANs, etc., and electronic appliances such as computers, etc. Electromagnetic wave absorbing sheets widely used at present are formed by metal sheets or nets, and electromagnetic wave absorbing sheets comprising vapor-deposited metal films formed on plastic sheets are recently proposed. For example, JP 9-148782 A proposes an electromagnetic wave absorbing sheet comprising a plastic film, and first and second vapor-deposited aluminum films formed on both surfaces of the plastic film, the first vapor-deposited aluminum film being etched in a non-conductive linear pattern, and the second vapor-deposited aluminum film being etched in a conductive network-shaped pattern.
WO 2010/093027 discloses a composite film comprising a single- or multi-layer, thin metal film formed on at least one surface of a plastic film, the thin metal film being provided with large numbers of substantially parallel, intermittent linear scratches with irregular widths and intervals in plural directions, thereby having reduced anisotropy of electromagnetic wave absorbability.
In the electromagnetic wave absorbing sheet of JP 9-148782 A and the composite film of WO 2010/093027 having a linear-scratched thin metal film, the electromagnetic wave absorbability is obtained by linear pattern or linear scratches. However, it is also desired to efficiently obtain an electromagnetic wave absorbing film having excellent electromagnetic wave absorbability by forming laser-beam-bored holes in a pattern.
Further, due to the demand of transparent electromagnetic wave absorbing films, electromagnetic wave absorbing films having thin ITO films or thin CNT films are proposed, and used for ETCs, etc. However, electromagnetic wave absorbing films used for ETCs are far-field electromagnetic wave absorbing films, which are not used as near-field electromagnetic wave absorbing films because of difficulty in impedance control for near-field electromagnetic waves. Thus desired is a near-field electromagnetic wave absorbing film comprising an opaque layer having electromagnetic wave absorbability, through which items can be viewed. Such characteristic is called “transmission viewability.”